Precision switch and method of construction



Nov. 28, 1961 I M. BAKELS 3,

' PRECISION SWITCH AND METHOD OF CONSTRUCTION Filed Sept. 50, 1958 La;r7 A 2 56 llllllllllllllllfi:lllllllllllllllllll E IIIIIIIII ATTORNEYS.brush element controlling the end of the impulse.

United States Pat-em O 3,011,841 PRECISION SWITCH AND METHOD OFCONSTRUCTION Marinus Bakels, Clifton, N.J., assignor to Unison ProductsCompany, Inc, Paterson, -N.J., a corporation of New Jersey Filed Sept.30, 1958, Ser. No. 764,367 6 Claims. (Cl. 200--166) This inventionrelates in general to rotary precision switches and particularly to amethod of constructing rotors and stators therefore having a. pluralityof angularly displaced precisely located conductive areas located alongannular areas in their respective external and internal peripheries.

Rotary precision switches of the character of which 'this invention isconcerned generally include a stationary brush element on the stator ora rotating rotor brush element arranged to contact conductive segmentsto deliver and receive electrical impulses as the switch rotor isrotated. this character, a greal deal of accuracy is required in thespacing of the conductive segments in either the rotor '01 the statordepending on which is provided with brush contact elements, in order tocontain precise delivery of electrical impulses. Such rotary precisioninstruments are primarily used for electrical control devices such astelemetering equipment in which both the duration and extent of anelectrical impulse is used to measure precise information. Variations inthe timing of the start and finish of such an impulse within a smallamount will create inaccuracies in the devices.

The present invention is directed to a method of assembling both rotorsand stators for small size rotary precision switches of theaforementioned character, inwhich segmental conductive portions areformed by precise gear forming methods, which are thereafter placed oninsulated discs. At least two discs are used for each of the conductiveimpulse areas which must be designed. Precise positioning of theconductive areas is achieved by placing two discs having precision cutconductive segment gear teeth thereon in side by side contact andadjustably rotating the disc until the conductive elements are arrangedin the desired angular spacing and extent. In such a method, it isnecessary to employ two brush contacting elements to contact thesegments of a pair of mating discs instead of the usual one. One of thediscs with its conductive element gear teeth segments is used to contacta brush element controlling the start of an electrical impulse and theother adjacent disc with its segments is used to contact 21 Thus, byrotating the discs relative to each other when the conductive areas areformed, it is possible to precisely position the conductive impulseareas so that control of the start and end of the electrical impulsetiming can be accomplished within very precise angular displacement.Thus,

for example, where it is desired to have sixty evenly spaced conductiveareas located at the outer periphery of a rotor, two gears of conductivematerial are fabricated, each having precisely cut thereon, sixty gearteeth. All of the spaces between the teeth are filled with insulationand the gear teeth are positioned on slotted insulated discs. The discsare then positioned adjacent one another and they are rotated to achievethe exact conductive element spacimpulsing may be obtained by correctpositioningof the disc elements in relation to each other rather than bycomplicated and expensive machining and aligning methods.

Accordingly, it is an object of this invention to provide In theconstruction of precision switches of Ice 3,011,041

Patented Nov. 28 1961 a method of forming angularly displaced conductiveareas for rotary precision switches.

A further object of the invention is to provide a method of aligning aplurality of conductive areas in an annular ring by mounting a gear ofconductive material on a slotted plastic disc and mounting a second gearof conductive material on a second slotted plastic disc, wherein each ofthe gear teeth formed in the gear are made with peripheral teeth areasof lesser peripheral extent than the conductive areas desired,positioningthe discs adjacent each other and aligning the discs tocorrectly space the conductive areas defined and thereafter securing thediscs together.

A further object of the invention is to provide a method ofmanufacturing rotary precision switches which provides a ruggedconstruction which is simple and economical to make. p

The various features of novelty which characterize the invention arepointed out with particularity in the claims annexed to and forming apart of this specification.

For a better understanding of the invention, its operating advantagesand specific objects attained by its use, reference should be had to theaccompanying drawings and descriptive matter in which there isillustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a transverse section of a rotary precision switch constructedin accordance with the invention;

FIG. 2 is a vertical section taken on the line 22 of FIG. 1;

FIG. 3 is a side elevation of a pair of conductive segment gear toothelements and mounting discs prior to their encapsulation;

FIG. 4 is a view similar to FIG. 3 but indicating internal conductivesegment gear elements;

' element combination;

FIG. 9 is avertical section taken along the line 99 of FIG. 8; and

FIG. 10 is a top plan of the rotor indicated in FIG. 7 with the segmentsof two gears combined and aligned to form a single conductive area forcontact by a two brush element.

Referring to the drawings in particular, the invention as embodiedtherein includes a precision rotary switch generally designated 10,having a rotor brush block 12 mounted on a shaft 14 for constantrotation thereby.

The rotor brush block 12 contains two sets of brushes generallydesignated 16 and 18 having brush elements which are biased into contactwith annular conductive areas 20, 22, 24, 26 and 28 of a statorgenerally desig nated 32.

In the present embodiment, the brush 16 includes a I brush element 34,which is arranged to contact a solid ring of conductive material 36provided in the annular conductive area 22 0f the stator 32. A solidbrush element 38 is connected to the brush element 34 and is arranged torotate with the rotor 12 in biased contact with an interruptedconductive ring 40 forming the annular conductive area 20 in the stator32. Similarly,

the brush 18 includes a brush element 42 arranged to contact a solidring of conductive material 44 in the an nular conductive area 24. Apair of double brush elements 46a, 46b and 48a and 4812 are connected tothe element 42. These double brush elements are arranged to contactinterrupted conductive element half segments 50 and 52 on the annularconductive areas 26 and 28, respectively. 1

Each of the solid ring conductors, the broken ring elementsrand theconductive segments are connected electrically by lead wires orterminals 54 which extend through an aperture 56' at the end of theprecision switch 10.

In accordance with the invention, the stator of such a switch is made inaccordance with the following method: Conductive segments 56 and 52 areformed by precision cutting conductive material into a gear or splineform having aprecise number of teeth with a precise spacingtherebetween. The gear may be either an external gear as at 56 or aninternal gear as at 58. Each of the gears is cut to define conductivesegment portions 60 and 62 for the gears 56 and 58, respectively, of aninternal surface and angular spacing required for precision electricalimpulsing. In this instance, the brush elements 34 and 42 are arrangedto receive a constant input electrical impulse from the solid conductiverings 36 and 44 and distribute these pulses through the leads 54 inprecise timed relation and duration, as the brush elements 46 and 48 and38, passthe interrupted conductive segment portions 50 and 52 and 20.

In accordance with the present invention, each of the gears 56 and 58are cut to provide gear teeth 64 and 66, respectively, which haveconductive segment portions 60 and 62 which are of slightly less angularextent and with slightlygreater angular displacement than will beactually required in the annular conductive areas for which they are tobe formed. The reason for this is that two such gears are combined toprovide one set of full conductive areas such as at 52. In such aninstance, a single brush element is replaced by the double brushelements such as 48a and 48b, one of which willcontact a left handconductive segment 52a and the other of which will contact a right handconductive segment 52b (FIG. 6).

After the gears 56 and 58 have been machined, the spaces between thegear teeth 64 and 66 are filled with an insulating material '78.Regardless of whether an internal or external gear is made, the gearsare positioned upon a plastic insulator disc 80 which in the case of theexternal gear 56 is later cut away to expose the conductive segments 60.

In accordance with the invention, an annular conductive area comprisinginterrupted conductive segment portions is formed by joining togethertwo similar gears such as the externalgear 56 each mounted on itsassociated disc 80. Before the set of disc and gear assemblies are fixedtogether they are adjusted angularly by rotating one gear with itsassociated segment to precisely locate a surface 82 for electricalimpulse start and a surface 84 for electrical impulse termination.

Thus, the previous method of precisely finishing the segment portionsfilling in with plastic, calibrating the spacing and then refinishingand refilling with plastic and conductive material by hand can beobviated.

Within the limits of the sizes of the gear teeth 64 which are cut, thegears may be rotated to obtain precise positioning between a left handportion gear segment 52a and a right hand portion gear segment 52b. Thediscs 80 are thenset in relation to each other by a set screw 90 whichis positioned through an arcuate slot 92 and tightly secured. The facesof the disc 80 are recessed as at 94 to permit the securing of plasticdisc spacer member brush thereto to form the remaining portion of thestator.

In the case of the external gear 56 after two gears have been joinedtogether and a precise positioning of the segment portions 52a and 522)has been achieved by rotating the assemblies, the segments are connectedindividually to the lead wires 54. The lead wires are then potted in aheat setting plastic 95 which is allowed to set up and harden.Thereafter, the discs 30 are removed from the center of the gears 56 anda rim 96 of the gear is cut away until the plastic 78 is reached and thesegments 66 are accurately defined.

In the case of the internal gear 58, it is necessary to cutaway a rim 98before the leads 54 are connected to the individual segments.Thereafter, the disc 80 is cut away and the interior bore is accuratelymachined to clearly define the segments 62 which will be arranged alongthe inner annular periphery of the stator.

The invention is equally applicable to the manufacture of rotors havinginterrupted annular conductive areas formed thereon, such as illustratedin FIGS. 7 to 10 inelusive. The rotor generally designated 100 includesa plastic hubbed sleeve 102, upon which is positioned a metallic bushing104 which carries a solid ring conductor 106 and an interruptedsegmental ring conductor gen erally designated 108.

The interrupted segmental ring conductor is formed in accordance withthe invention by first forming an external gear 110 with the precisenumber of gear teeth 112 to give the desired number of segmentalconductive areas. The gear teeth 112 are made smaller, and with aspacing larger, than will be actually required. The spaces between theteeth are filled with heat setting plastic insulation 114 and the gearis mounted on a plastic disc 116 having an arcuate slot 117. When twosuch assemblies are made and they are positioned into close engagement(FIG. 9), the disc assemblies are then rotated until the desiredconductive areas from a starting peripheral contact line 118 of the leftgear disc assembly and a finish peripheral contact line 120 of a rightgear disc assembly to thus define the correct conductive area angularextent (FIG. 9).

Once the assemblies are accurately aligned they are held in position bya set screw 122 which is positioned in the slot 117. Each disc 116 issuitably recessed at 124 to provide clearance for the screw heads oneach side and permit close fitting of a plurality of assemblies. In theoperation of such a rotor two laterally spaced brush elements for eachconductive area are required to sweep around the rotor periphery, one incontact with 'each segment instead of the usual one. Electrical contactis made by one brush and stopped by the other since the conductive areasare angularly displaced.

Thus the invention provides a simple means for the precision making ofsmall diameter rotary switches. It is possible with the invention, bymaking up a plurality of discs with interrupted segmental conductiveareas thereon of varying angular extent and angular spacing to achieveany electrical impulsing desired by uniting a plurality thereof to formthe desired conductive areas. Use of either two, three or even fourbrush elements in conjunction with two or more joined disc segments maybe used to give any electrical impulse timing and extentrequired in arotary switch. The invention greatly simplifies the construction of suchswitches and reduces the time for the assembly thereof as well asgreatly increases the accuracy thereof.

While specific embodiments of the invention have been shown anddescribed in detail to illustrate the application of the inventionprinciples, it will be understood that the invention may be embodiedotherwise without departing from such principles.

I claim:

1. A precision switch rotor having at least one peripheral annularelectrically conductive area comprising spaced conductive segmentsinterrupted by insulation wherein said conductive area includes at leasttwo conductive material gear like elements having a plurality of teethcorresponding in number to the desired number of conductive segments butangularly spaced a slightly greater amount than the segments which areformed thereby, said elements being positioned on side by side touchingelectrical engagement but with the teeth thereof offset a precise amountto define the beginning of each conductive segment by the forward edgeof the gear of one element, and the end of each conductive segment bythe trailing edge of the gear of another segment.

2. A rotor according to claim 1 wherein said gear like elements are atleast two gears having a plurality of angularly spaced teeth each havingflat peripheral portions defining conductive areas. I i

3; A precision switch rotor having at least one peripheral annularelectrically conductive area comprising spaced conductive segmentsinterrupted by insulation wherein said conductive area includes at leasttwo conductive material gear like elements formed from an external gearhaving a plurality of teeth corresponding in number to the desirednumber of conductive segments but angularly spaced a slightly greateramount than the segments which are formed thereby, said elements beingpositioned on side by side touching electrical engagement but with theteeth thereof oflset a precise amount to define the beginning of eachconductive segment by the forward edge of the gear of one element, andthe end of each conductive segment by the trailing edge of the gear ofanother element. 9

4. A precision switch stator having at least one internal annularelectrically conductive area comprising spaced conductive segmentsinterrupted by insulation wherein said conductive area includes at leasttwo conductive material gear like elements having a plurality of teethcor responding in number to the desired number of conduc: tive segmentsbut angularly spaced a slightly greater amount than the segments whichare formed thereby,

6 said elements being positioned on side by side touching electricalengagement but with the teeth thereof offset a precise amount to definethe beginning of each conductive segment by the forward edge of the gearof one element, and the end of each conductive segment by the trailingedge of the gear of another element 5. A stator according to claim 4wherein said gear like elements are at least two internal gears having aplurality of angularly spaced teeth eachhaving flat internal peripheralportions defining conductive areas.

6. A precision switch stator having at least one internal annularelectrically conductive area comprising spaced conductive segmentsinterrupted by insulation wherein said conductive area includes at leasttwo conductive material external gears having a plurality of teethcorresponding in number to the desired number of conductive segments butangularly spaced a slightly greater amount than the segments which areformed thereby, said elements being positioned on side by side touchingelectrical engagement but with the teeth thereof offset a precise amounttodefine the beginning of each conductive segment by the forward edge ofthe gear of one element, and the end of each conductive segment by thetrailing edge of the gear of another element, conductive leadsconnecting each of said gears, and insulation encasing said gears andsaid leads, the interior rim of said external gear being cut away toexpose the inner ends of said gears.

References Cited in the file of this patent UNITED STATES PATENTS2,133,980 Fowlor Oct. 25, 1938 2,681,393 Hopkins June 15, 1954 2,749,397Brown June 5, 1956 2,825,960 Protz Mar. 11, 1958 2,832,127 Felts Apr.29, 1958 2,853,563 Bole Sept. 23, 1958

